Flexible detonation wave shaping device



March 4, 1969 R. H. F. STRESAU FLEXIBLE DETONATION WAVE SHAPING DEVICE Filed Aug. 7, 1963 Hill.

INVENTOR. RICHARD H. F. STRESAU BY IV ATTYS.

United States Patent 3,430,563 FLEXIBLE DETONATION WAVE SHAPING DEVICE Richard H. F. Stresau, Spooner, Wis., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Aug. 7, 1963, Ser. No. 300,960 US. Cl. 102-22 Int. Cl. F42b 3/02; F42d 1/04 This invention relates to explosive devices and more particularly to a new and improved surface-wave generator or detonation wave shaping system wherein a detonation front initiated at one point is made to arrive simultaneously at a plurality of points on a desired surface, the configuration of which may be either plane or curved.

Detonating wave shaping devices heretofore devised comprise a number of means for achieving the desired result including simultaneous or programmed initiation by a large number of electric initiators, lens systems in which Huygens principle is applied to explosives of differing propagation rates, waves interrupted by inert barriers, systems in which detonation is transmitted between charges by flying plates or fragments, and arrays of detonating cord or sheet explosive. Another system involving multiple layers of flexible sheet explosive material separated and supported by an inert elastomer was disclosed in an application by Richard H. F. Stresau, Jr., Ser. No. 192,748 filed May 7, 1962, and now abandoned.

Each of the foregoing systems possesses certain inherent disadvantages. The multiple electric detonator systems, for example, involve either the hazard of large numbers of sensitive devices or the cost and bulk of high powered firing systems. The binary explosive and moving metal systems must be especially designed for each detonation wave configuration desired. The arrays of prima-cord or sheet explosive require much detailed effort for each charge. The multilayer design, with a sufliciently large number of initiation points, might be too thick for some applications.

The present invention possesses all the advantages of the prior art devices and none of the foregoing disadvantages.

In accordance with the teaching of the present invention this desirable result is achieved by a matrix of new and improved configuration embedded within a sheet of inert elastomer in such manner that a detonation wave emerging from a central point within the elastomer traverses a plurality of equal length explosive trains to a plurality of explosive termini arranged in uniform spaced relation at the surface of the sheet of elastomer thereby to initiate the main explosive charge simultaneously at points corresponding respectively to the termini in contact therewith, as will more clearly appear as the description proceeds.

One of the objects of the present invention is to provide a new and improved single layer explosive device in which the detonation that originated at one point therein is directed to arrive simultaneously at a plurality of points on a surface.

Another object of the present invention is the provision of a new and improved surface wave generator of minimum thickness which is suitable for producing a plurality of wave front configurations, both plane or curved.

A still further object of the present invention is to provide a new and improved surface wave generator formed of flexible materials and having a single layer matrix of flexible explosive embedded therein and con figured to produce simultaneous detonation at a plurality of uniformly spaced points on the surface of the generator in accordance with the configuration of the main explosive charge with which the explosive termini are in contact.

5 Claims ice Other objects, advantages and novel features of the present invention will become apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawing wherein:

FIG. 1 is a plan view partially in section and partially broken away of a surface wave generator embodying the present invention, and

FIG. 2 is a view taken along line 22 of the device of FIG. 1 and illustrating a fragmentary view of the main explosive charge in closely abutting relation therewith.

Referring now to FIG. 1 of the drawing for a more complete understanding of the invention there is shown thereon a surface wave generator indicated generally by the numeral 10 comprising a single sheet of flexible sheet explosive 11 configured substantially as shown and embedded in a matrix of inert elastomer 12. The flexible sheet explosive may be of any type suitable for the purpose such, for example, as a type known in the trade as EL-506, a product of the E. I. du Pont Co. The matrix is configured, as will be apparent from a casual inspection of the drawing, to provide an explosive train 13 extending from an exterior point 14 to a central portion of the device indicated at 15 from which the detonation wave proceeds and arrives simultaneously at points 16, 17, 18 and 19 from whence the detonation wave continues to points 21 to 36 and arrives simultaneously thereat. The matrix is configured at each of the points 21-36 to provide two L-shaped arms of equal length and a T- shaped arm, the length of each end of the T portions of the arm to the common point of connection with the L- shaped arms being the same as the length of each L- shaped arm. The outer end of each of the L-shaped arms is bent to a position forming substantially a right angle with respect to the lateral portion of the L-shaped arm to define an extension brought out flush with the surface of the elastomer 12 to form an explosive terminus 37 and in like manner the T-configured arms are formed at a right angle with extensions brought out to the surface of the sheet of inert elastomer 12 as at 38, FIG. 2.

An arrangement is thus provided in which 64 termini 37-38 are arranged like a checker board to provide 64 uniformly spaced explosive termini in which the arrival of the detonation is simultaneous when the explosive network is init-iated at the common origin 14. When the surface wave generator 10 is applied to an explosive charge such as the charge 39, FIG. 2, having a planar surface therebetween, the detonation Wave imparted to the explosive 39 is planar in character. If, on the other hand, the surface of the main explosive 39 were curved to a desired configuration and the surface wave generator 10 were brought into close fitting contact therewith, the detonation wave imparted to the main explosive 39 would correspond in character to the curvature of the surface between the surface wave generator and the main explosive charge.

It will be noted that the explosive network is configured to provide a plurality of groups of straight line portions, the first group comprising the equal length portions 15- 16; 15-17; 15-18 and 15-19, the second group comprising the equal length portions 16-21; 16-22; 16-25 and 16-26: 17-23, 17-24; 17-27 and 1 7-28: 18-31; 18-32; 18-35 and 18-36: 19-29; 19-30; 19-33 and 19-34, and the third group comprising the equal length portions from the points of intersections 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 and 32 to the 64 explosive termini 37-38 connected thereto. The portions comprising each group are of equal length and the portions comprising each successive group are progressively of lesser length than the portions of the immediately preceding group with which it is connected.

It will be noted that an arrangement is thus provided in which the path along the sheet explosive network between the common origin and each terminus is equal to that between the origin and each other terminus and the arrival of the detonation at all termini, therefore, is simultaneous if the network is initiated at the origin. The layer of inert elastomer between the network and the main charge is sufiiciently thick to protect the main charge from damage or initiation by the network except at the termini aforesaid, and the distance between each of the arms forming the explosive train of the network is spaced at a distance from each adjacent arm suflicient to prevent the shock wave from detonating an adjacent arm except through the exposive train provided therebetween. The cross-sectional area of the various arms of the network is not critical, it being merely necessary that the cross-sectional area be uniform throughout the length of the arms and of sufiicient cross-sectional size to insure reliable propagation of the detonation wave therealong without the possibility of cross-fire between adjacent arms as a result of brisance.

-An important consideration in the choice of explosive forming the flexible network is that it must detonate at a uniform velocity throughout the length of the various paths from the source of initiation to the various termini to achieve simultaneous detonation thereat.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A flexible detonation wave shaping device comprising a flexible sheet of inert elastomer configured to a matrix and a flat sheet of flexible sheet explosive embedded in said matrix in a manner to form an explosive network characterized by a plurality of coplanar explosive trains interconnected to a common origin, said sheet of flexible explosive, including said common origin, being embedded in a median area between the opposite surfaces of said sheet of elastomer, said trains each being of equal length and each having at its terminal end an extension comprising a length of explosive configured normal to the surface of said sheet of inert elastomer and terminating substantially flush therewith to thereby form a plurality of termini spaced uniformly over the group being of equal length and the portions of each successive group being progressively less in length than the portions in the immediately preceding group.

3. A wave shaping device accord-ing to claim 1 in which the cross-sectional area of each of said explosive trains is uniform and just sufficient to reliably support a detonation wave therealong.

4. A wave shaping device according to claim 3 in which the sheet of inert elastomer is of just sufficient thickness to confine the detonation wave to said straight line portions as the wave travels from said common origin to the termini when the device is applied to matching relation with the surface of a main explosive charge of either planar or curved configuration.

5. Means for initiating an explosion simultaneously at a plurality of points distributed uniformly over a surface of a body of explosive material comprising:

a flat square block of flexible inert elastomer capable of being conformed to the surface of the explosive material to be detonated, and

a flexible sheet explosive embedded in said elastomer and spaced from and substantially parallel to the mating surfaces of said elastomer and said explosive material, said sheet explosive being arranged in a pattern which provides a plurality of equilength explosive trains extending from a common origin at one side of said elastomer to said plurality of points as follows: a first train extending to the center of said square block and there branching into two L-shaped trains and a T-shaped train, the ends of which lie at the centers of the quadrants of the square and each train in turn branching into two shorter L-shaped trains and a T-shaped train, the branching continuing until all the available space is occupied, the terminal ends of all the trains then extending out to the mating surface of said elastomer.

References Cited UNITED STATES PATENTS 2,774,306 12/1956 MacLeod '102-70 2,943,571 7/1960 Coursen 102-22 3,035,518 5/1962 Coursen 10222 2,999,458 9/ 1961 Coursen 102-22 VERLIN R. PENDEGRASS, Primary Examiner.

U .8. Cl. XJR. 

1. A FLEXIBLE DETONATION WAVE SHAPING DEVICE COMPRISING A FLEXIBLE SHEET OF INERT ELASTOMER CONFIGURED TO A MATRIX AND A FLAT SHEET OF FLEXIBLE SHEET EXPLOSIVE EMBEDDED IN SAID MATRIX IN A MANNER TO FORM AN EXPLOSIVE NETWORK CHARACTERIZED BY A PLURALITY OF COPLANAR EXPLOSIVE TRAINS INTERCONNECTED TO A COMMON ORIGIN, SAID SHEET OF FLEXIBLE EXPLOSIVE, INCLUDING SAID COMMON ORIGIN, BEING EMBEDDED IN A MEDIAN AREA BETWEEN THE OPPOSITE SURFACES OF SAID SHEET OF ELASTOMER, SAID TRAINS EACH BEING OF EQUAL LENGTH AND EACH HAVING AT ITS TERMINAL END AN EXTENSION COMPRISING A LENGTH OF EXPLOSIVE CONFIGURED NORMAL TO THE SURFACE OF SAID SHEET OF INERT ELASTOMER AND TERMINATING SUBSTANTIALLY FLUSH THEREWITH A THEREBY FORM A PLURALITY OF TERMINI SPACED UNIFORMLY OVER THE AREA OF ONE SURFACE OF SAID ELASTOMER SHEET WHEREBY AN EXPLOSIVE CHARGE WITH WHCIH THE SURFACE IS BROUGHT INTO CONTACT IS DETONATED SIMULTANEOUSLY AT A PLURALITY OF POINTS CORRESPONDING RESPECTIVELY TO SAID TERIMII IN RESPONSE TO A DETONATION WAVE APPLIED TO THE COMMON ORIGIN OF SAID NETWORK. 